There are already several plugins to creates paths with geometrical shapes, but they all require tedious entry of numbers in some dialog.

So this plugin uses a radically different method: the significant points are entered as points in a path stroke, and then the plugin us called without any explicit parameters (there is a menu entry for each shape/interpretation of the path, so they can be assigned to a keyboard shortcut).

Create a NPOT (nearest power of two) square background colored sprite sheet that can contain at least N sprites of the given width and height with optional spacing between each sprite. Also creates guides to show the limits of these sprites.

ALSO:
Image/Guides/Sprite Sheet Guides...
Creates guides on the current image for sprites of the given height, width, and spacing.

This plugin adds a lens with border/shadow to an image.
Developed with 2.8, other untested.

Usage:
- select a part from the image that you will make a lens for (use circle selection)
- make your prefered settings in the dialog
- to get a positiv look, scale image down or check that your selection is < as desired lens size so it scaled up

Not perfekt but a good first throw i guess.
I commented it well, could be usefull for other newbies. I had a hard time to figure it out.